Aeroelasticity

About: Aeroelasticity is a research topic. Over the lifetime, 7804 publications have been published within this topic receiving 122172 citations.

Wingmill: An Oscillating-Wing Windmill

Abstract: This article describes an analytical and experimental investigation of a windmill which utilizes a harmonically oscillating wing to extract wind energy. In particular, the wing's span is horizontally aligned and the airfoil is a chordwise-rigid symmetrical section. The whole wing oscillates in vertical translation and angle-of-attack, with prescribed phasing between the two motions. A theoretical analysis was developed utilizing unsteady-wing aerodynamics from aeroelasticity and the results guided the design of a working model for wind-tunnel experiments. For the cases tested, theory and experiment compared favorably, and showed the wingmill to be capable of efficiencies comparable to rotary designs.

Analytical aeropropulsive-aeroelastic hypersonic-vehicle model with dynamic analysis

Abstract: The determination of the dynamic characteristics of hypersonic vehicles requires an integrated approach since the propulsion system and airframe are so highly coupled. The forces and moments arise from both aerodynamic and propulsive sources, which are for these configurations hard to separate. Offered herein is a first step toward the development of such an approach that is intentionally generic and basic. Further, analytical expressions are developed to allow for characterization of the vehicle's dynamics early in the design cycle, so that configuration trade-offs may be performed with some cognizance of the attitude dynamics. The method of approach involves a two-dimensional hypersonic aerodynamic analysis utilizing Newtonian theory, coupled with a one-dimensional aero/thermo analysis of the flow in a SCRAMjet-type propulsion system. In addition, the airframe is considered to be elastic, and the structural dynamics are characterized in terms of a simple lumped-mass model of the in vacuo vibration modes. The vibration modes are coupled to the rigid-body modes through the aero/propulsive forces acting on the structure. The control effectors considered on a generic study configuration include aerodynamic pitch-control surfaces as well as engine fuel flow and diffuser area ratio. It is shown that the vehicle's aerodynamics and propulsive forces are both very significant in the evaluation of key stability derivatives that dictate the vehicle's dynamic characteristics. It is also shown that the vehicle model selected is highly unstable in pitch and exhibits strong airframe/engine/elastic coupling in the aeroelastic and attitude dynamics. With the use of literal expressions for both the system's poles and zeros as well as the stability derivatives, key vehicle dynamic characteristics are investigated. For small errors, or uncertainties, in either the aerodynamic or propulsive forces, significant errors in the frequency and damping of the dominant modes and zero locations will arise. AD AN b Cp g h /i h L L i

Flight Dynamics of Highly Flexible Flying Wings

Abstract: The paper presents a theory for flight-dynamic analysis of highly flexible flying-wing configurations. The analysis takes into account large aircraft motion coupled with geometrically nonlinear structural deformation subject only to a restriction to small strain. A large motion aerodynamic loads model is integrated into the analysis. The analysis can be used for complete aircraft analysis including trim, stability analysis linearized about the trimmed-state, and nonlinear simulation. Results are generated for a typical high-aspect-ratio "flying-wing" configuration. The results indicate that the aircraft undergoes large deformation during trim. The flight-dynamic characteristics of the deformed aircraft are completely different as compared with a rigid aircraft. When the example aircraft is loaded sufficiently, the pair of complex-conjugate short-period roots merges to become two real roots, and the phugoid mode goes unstable. Furthermore, nonlinear flight simulation of the aircraft indicates that the phugoid instability leads to catastrophic consequences.